Abstract: In order to design the steering-by-wire system that met the requirements of handling stability, an ideal transmission ratio control strategy that could adapt to different vehicle speed conditions was proposed. Based on the transmission ratio with constant steady-state yaw rate gain, three speed ranges such as low-speed range, medium-speed range and high-speed range were set. Based on the constant steady-state yaw rate gain in parameter fitting and constant steering gain control method, the ideal transmission ratio of low-speed range and medium-speed range was designed. Considering the influence of nonlinear factors such as friction characteristics in the high-speed range, fuzzy control was used to design the ideal transmission ratio of the steering-by-wire system. And the effectiveness of the ideal transmission ratio control strategy designed at different vehicle speeds was analyzed through Carsim and Simulink simulations. The research results show that in the low-speed range, the steering motion characteristics of the vehicle are significantly improved, enhancing the vehicles steering sensitivity. In the medium-speed range, the vehicles steering response follows well and responds faster. In the high-speed range, the steering stability of the vehicle during driving is significantly improved.

Key words: vehicle engineering; steering-by-wire system (SBW); ideal transmission ratio; joint optimization; handling stability

摘要： 为设计满足操纵稳定性需求的线控转向系统，提出了可适应不同车速工况的理想传动比控制策略。以稳态横摆角速度增益不变下的传动比为基础，设置低速段、中速段、高速段等3个车速区间；基于参数拟合和定转向增益不变控制法中的稳态横摆角速度增益不变，设计了低速段和中速段的理想传动比，高速段考虑到摩擦特性等非线性因素影响，使用模糊控制设计线控转向系统理想传动比；通过Carsim和Simulink仿真分析了在不同车速下设计理想传动比控制策略的有效性。研究结果表明：在低速段时，车辆转向运动特性明显提高，增强了车辆的转向灵敏性；在中速段时，车辆转向响应跟随性好，且响应速度更快；在高速段时，车辆行驶时的转向稳定性明显提高。

关键词: 车辆工程；线控转向系统(SBW)；理想传动比；联合优化；操纵稳定性